Cruise control for vehicle

ABSTRACT

The present invention relates to a motor vehicle comprising an internal combustion engine and a first electronic control unit ( 48 ) for controlling the engine depending on the setting of a manual throttle, an electronic control unit ( 45 ) for controlling the transmission, depending on a set position of a manual gear selector ( 46 ). The invention is characterized in that one of the control units is disposed, with fed-in parameters and thus at least knowledge of the target speed of the vehicle, the surrounding topology and the throttle opening position, to reduce the throttle opening, in those cases where the vehicle, relative to the target speed, has a speed below target speed and gravity can subsequently accelerate the vehicle. In a similar manner, the kinetic energy of the vehicle is used, in those cases where the vehicle has an above target speed and gravity can subsequently retard the vehicle.

FIELD OF THE INVENTION

The present invention relates to motor vehicle comprising an internalcombustion engine and an electronic control unit for controlling theengine depending on the setting of a manual throttle, an electroniccontrol unit for controlling the transmission, depending on a setposition of a manual gear selector.

BACKGROUND OF THE INVENTION

In vehicles of this type there are today control units with a storedgear selector strategy, i.e. a time-based shifting sequence as afunction of road incline, for example. A known technology is describedin U.S. Pat. No. 5,832,400. For vehicles with a conventional automatictransmission, where the transmission shifts sequentially with a torqueconverter, there is a gear selection strategy based on an algorithmwhich takes into account a measuring point in the topology surroundingthe vehicle, with instantaneous vehicle position as a reference point.By determining, by various methods, where the vehicle will be after acertain time interval, it is possible to modify the engine setting andthe shifting points for the automatic transmission, i.e. at which rpmthe transmission should shift up or down. Possible variants could be touse electronic maps together with a positioning system (e.g. a GlobalPositioning System, GPS) or extrapolate a future position for thevehicle. One disadvantage of this system is that it does not take intoconsideration how the road varies in elevation between two points ofmeasurement, and extreme points (e.g. the crest of a hill) between thetwo points of measurement are thus not taken into account in certaincases. The engine and the transmission are set in accordance with theknown technology, on the basis of how great the difference in elevationis between the two points of measurement, and the instantaneous throttleposition. Throttle position means in this case and in the following textboth an adjustable cruise control and an accelerator pedal.

U.S. Pat. No. 5,832,400 only takes into consideration, as was mentioned,a single point of measurement during a certain time or distance into thefuture, in order to see if the instantaneous engine torque will besufficient, or if the engine and/or transmission needs to be reset. Itis also described how a plurality of points of measurement can be usedbut in that case a mean value thereof is used, thus providing one valuefor the required driving force. With a transmission which is shiftedsequentially and with the method just described, there is an uncertaintyin the system which results in tangible consequences in the form of lessthan satisfactory cruise control function, uneven acceleration andunnecessarily large exhaust emissions.

Today, cruise controls function by controlling a throttle opening or abraking process, which is described in U.S. Pat. No. 5,894,731, until aselected or given target speed in reached. In practice this means thatif a vehicle is moving downhill at a speed exceeding the target speed,the cruise control will attempt to brake the vehicle down to the targetspeed, regardless of the road incline after the end of the downhillstretch. This means that if, directly after the downhill stretch, thereis an uphill incline, and the vehicle has been braked down to the targetspeed, the vehicle, if the uphill stretch is sufficiently steep, willmove at below the target speed. The cruise control, in this situation,will compensate by greatly increasing the throttle opening and shiftingdown. Another example of the same type of problem is the case of theextension of the problem just described, where the vehicle is movinguphill at lower than target speed and reaches the crest, whereupon thecontinued open throttle will result in excess speed in the subsequentdownhill stretch, and the vehicle will be forced to brake to once againreach the target speed.

There are today other types of cruise controls, for example those whichuse radar and adjust the vehicle speed to traffic in front, ortransponders mounted on road signs for example. In both cases the targetspeed of the vehicle is changed continually depending on the surroundingtraffic, weather conditions, wild animals other dynamic or randomparameters. The purpose of the present invention is to achieve a motorvehicle of the type described by way of introduction, which removes theabove mentioned problems by providing a system and a method, which, withthe aid of a cruise control function, controls throttle opening andbraking, where the braking is effected using auxiliary brakes forexample, to obtain lower vehicle fuel consumption. There are alsoachieved lower noise and exhaust emissions, more even acceleration andmore comfortable cruising.

SUMMARY OF THE INVENTION

This is achieved in a vehicle of the type described by way ofintroduction according to the invention by virtue of the fact that oneof the control units is disposed, with fed-in parameters and thus atleast knowledge of the target speed of the vehicle, the surroundingtopology and the throttle opening position, to reduce the throttleopening, in those cases where the vehicle, relative to the target speed,has a speed below target speed and gravity can subsequently acceleratethe vehicle, and to use the kinetic energy of the vehicle, in thosecases where the vehicle has a speed above the target speed and gravitycan subsequently retard the vehicle.

In a preferred embodiment, the second control unit is disposed, underset preconditions, to perform computer simulations for a longer periodforward (30 seconds or more), where the information on instantaneousposition is obtained with the aid of GPS and/or where future positionsare provided by information from an electronic map.

In a second embodiment, with the aid of electronics and sensors,estimates, (extrapolations) can be made concerning road incline andinformation can thus be obtained on the topology surrounding the vehicleand its future position.

The present invention is preferably intended for, but is not limited to,automated manual transmissions. A significant difference in relation tothe known technology (Automated Power Transmission) referred to, is thatshifting in the present case takes place with force interruption. Thereis thus a clear advantage of using the system according to theinvention, otherwise it is not certain that shifting up in an up-hillincline will be successful, even if the driving force were theoreticallysufficient because if the shifting takes too long, the vehicle will beretarded too much.

With reference to the two cases (too low speed in an uphill incline andexcessive speed in a downhill incline) which were exemplifiedpreviously, the present invention could in principle be summarized asfollows:

-   -   1) At the request of the driver, with the aid of electronics and        data from sensors, the second control unit, upon a decision        based on a computer simulation, can deactivate applied auxiliary        brakes, which would otherwise apply bracing torque, when the        vehicle, without the braking torque, would achieve reduced fuel        consumption and/or increased average speed.    -   2) At the request of the driver, with the aid of electronics and        date from sensors, the second control unit, upon a decision        based on a computer simulation, can adjust the throttle opening        of a cruise control to the current driving resistance of the        vehicle and that in the immediate future (30 seconds or more).

In order to additionally describe the present invention a few exampleswill be provided below of applications.

The second control unit is disposed, with the aid of electronics andsensors, to limit the throttle opening when there are large speeddeviations and when the road is inclined downhill.

The second control unit is disposed, with the aid of electronics andsensors, to keep the throttle open when the vehicle speed is greaterthan that set in the cruise control and the vehicle is approaching anuphill incline in which the reduction in speed would be so great thatthe maximum engine torque would not be able to accelerate the vehiclebefore the vehicle speed has dropped to the target speed.

The second control unit is disposed, with the aid of electronics anddata from sensors, to adjust the throttle opening when the vehicle isapproaching the end of an uphill incline, and where the vehicle speed isless than the target speed, gradually adjusting to a future lesserthrottle opening.

The second control unit, with the aid of electronics and sensors, isdisposed to adjust the throttle opening, when the vehicle approaches thebeginning of a downhill incline, to gradually adjust to a future lesserthrottle opening, i.e. the throttle opening which together with gravityand driving resistance will accelerate the vehicle to the target speedwithin a predetermined time period.

The second control unit, with the aid of electronics and sensors, isdisposed to adjust possibly applied auxiliary brakes and possibly thethrottle opening, as the vehicle approaches the end of a downhillincline, to a future greater throttle opening required to maintain thetarget speed.

The second control unit, with the aid of electronics and sensors, isdisposed to adjust possibly applied auxiliary brakes and possibly thethrottle opening, as the vehicle approaches the end of a downhillincline, so as to permit a temporary increase in speed, the maximumlevel of which is predetermined in the second control unit.

The second control unit, with the aid of electronics and sensors, isdisposed to release the auxiliary brakes, when the vehicle approaches anuphill incline and where the vehicle speed exceeds the target speed, tonot brake off energy since the retardation of the vehicle in the uphillincline will adapt the vehicle speed to the target speed.

In the above description and in the following, it is stated that thevarious input data are fed into the second control unit which carriesout the computer simulations. This function can, of course, also betaken over by the first control unit or at another physical locationarranged for communication with the second control unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail below with reference toexamples shown in the accompanying drawings, where

FIG. 1 shows a schematic representation of one embodiment of a driveunit according to the invention,

FIG. 2 shows the clutch and the gearbox in FIG. 1 on a larger scale, and

FIG. 3 shows an overview of inputs into the second control unit.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, 1 designates a six-cylinder internal combustion engine, e.g.a diesel engine, the crankshaft 2 of which is coupled to a single-platedry disk clutch which is designated generally by reference number 3 andis enclosed in a clutch case 4. Instead of a single-plate disk clutch, adual disk clutch can be used. The crankshaft 2 is connectednon-rotatably to the clutch housing 5 of the clutch 3, while its diskplate 6 is connected non-rotatably to an input shaft 7, which is mountedrotatably in the casing 8 of a gearbox designated generally by referencenumber 9. A main shaft 10 and an intermediate shaft 11 are also mountedrotatably in the casing 8. Further, there are illustrated a firstcontrol unit 48 for controlling the engine, a second control unit 45 forcontrolling the transmission and a manually operated electronicgear-speed selector 46, coupled to the second control unit 45. Auxiliarybrakes 60 are controlled from and second control unit via the firstcontrol unit 48. The auxiliary brakes can be for example compressionbrakes or exhaust brakes. The first and second control units (48 and 45,respectively) are adapted for communication with each other.

As can be seen most clearly from FIG. 2, a gear wheel 12 is mountedrotatably on the input shaft 7 and is lockable on the shaft by means ofan engaging sleeve 13 which is provided with synchronizing means and ismounted non-rotatably but axially displaceably on a hub 14 connectednon-rotatably to the input shaft 7. By means of the engaging sleeve 13,a gear wheel 15 mounted rotatably on the main shaft 10 is also lockablerelative to the input shaft 7. The gear wheels 12 and 15 engage withgear wheels 16 and 17, respectively, which are connected non-rotatablyto the intermediate shaft 11. Arranged in a rotationally fixed manner onthe intermediate shaft 11 are further gear wheels 18, 19 and 20 whichengage with gear wheels 21, 22 and 23, respectively, which are mountedrotatably on the main shaft 10 and are lockable on the main shaft bymeans of engaging sleeves 24 and 25, respectively, which, in theillustrative embodiment shown, do not have synchronizing arrangements. Afurther gear wheel 28 is mounted rotatably on the main shaft 10 andengages with an intermediate gear wheel 30, which is mounted rotatablyon a separate shaft 29 and engages in turn the intermediate shaft gearwheel 20. The gear wheel 28 is lockable on its shaft by means of anengaging sleeve 26.

The gear wheel pairs 12, 16 and 15, 17 and also the engaging sleeve 13form a split gearing with a low gear stage LS and a high gear stage HS.The gear wheel pair 15, 17 also forms, together with the gear wheelpairs 21, 18, 22, 19, 23, 20 and 28, 30, a basic gearbox with fourforward gears and one reverse gear. Arranged in a rotationally fixedmanner on the output end of the main shaft is a gear wheel 31 whichforms the sun gear in a two-stage range gear of the planetary typedesignated by reference number 32, the planet wheel carrier 33 of whichis connected in a rotationally fixed maimer to a shaft 34 which formsthe output shaft of the gearbox. The planet wheels 35 of the range gear32 engage with a ring gear 36, which, by means of an engaging sleeve 37,is lockable relative to the gearbox casing 8 for low range LR andrelative to the planet wheel carrier 33 for high range HR. The engagingsleeve also has a neutral position NR between the gear positions LR andHR. In the neutral position NR the output shaft 34 is released from themain shaft 10.

The engaging sleeves 13, 24, 25, 26 and 37 are displaceable as shown bythe arrows in FIG. 2, to provide the gear stages shown next to thearrows. The displacement is brought about by servo devices 40, 41, 42,43 and 44 which are indicated diagrammatically in FIG. 2 and may bepneumatically operated piston/cylinder arrangements of the type used ina gearbox of the type described above, which is marketed under the nameGeartronic®. The servo devices are controlled by an electronic controlunit 45 (FIG. 1), comprising a microcomputer, depending on signals fedinto the control unit representing the various engine and vehicle datawhich comprise at least engine speed, vehicle speed, throttle pedalposition and, in this case, engine brake on/off, when an electronic gearselector 46 coupled to the control unit 45 is in its automatictransmission position. When the selector is in the position for manualshifting, shifting is effected via the gear selector 46 at the commandof the driver. The control unit 45 also controls fuel injection, that isto say the engine speed, depending on the throttle pedal position, andalso the air supply to a pneumatic piston/cylinder arrangement 47, bymeans of which the clutch 3 is engaged and disengaged.

The second control unit 45 is programmed in a known manner so that itkeeps the clutch 3 engaged when the vehicle is standing still and thegear selector 46 is in the neutral position. This means that the enginedrives the input shaft 7 and thus also the inter-mediate shaft, whilethe output shaft 34 is disengaged. An auxiliary unit, e.g. an oil pumpfor lubricating the gearbox, can possibly be driven by the intermediateshaft in this position. The second control unit 45 is also programmed,when the vehicle is standing still and the gear selector is moved fromthe neutral position to a shift position, either to a position forautomatic shifting or to a position with a start-off gear selected bythe driver, to first release the clutch 3, then brake the intermediateshaft 11 to stop with the aid of the intermediate shaft brake 50,indicated in FIG. 2, which can be a brake device, which can be known perse, controlled by the control unit 45. With the intermediate shaft 11braked to stop or at least nearly to stop, the control unit 45 nowinitiates the shift in the basic gearbox to a gear ratio which isprovided by the automatic shifter or selected by the driver. When thedriver, after engaging the gear, opens the throttle, the acceleratorpedal functions as a reverse clutch pedal, which, via the control unit,gradually increases the clutch engagement with increasing throttleopening.

FIG. 3 illustrates schematically input which the second control unit 45needs to be able to male a decision to close the throttle opening orbrake the vehicle in accordance with the present invention. With onecontrol 300 for manual turning on or off of the present function, thedriver can actively select the process. The switch 300 is adapted forcommunication with the second control unit 45. An electronic map 340,for example stored on a CD-ROM (Compact Disc Read Only Memory) containsthe information on a region's topology necessary for the computersimulation, i.e. at least gradients or elevation values for the route,with sea level as a reference, for example, and any informationconcerning speed limits along the route. The computer simulation usesparameters 320 sent from meters and sensors 310, in accordance withknown technology. These consist at least of vehicle or train weight,instantaneous vehicle speed, gear ratios, degrees of efficiency, enginerpm, throttle opening position (even throttle opening position change),instantaneous position, road incline (not from electronic map), ambienttemperature (which affects the fuel/air mixture), driving resistance andthe engine dynamics of the engine. With the necessary information, thesecond control unit 45 can compute (simulate over a certain,predetermined time) i.a. estimated, future required acceleration(orretardation) and fuel consumption. Furthermore, FIG. 3 shows a symbolfor GPS 330, which communicates with the second control unit, possiblyalso through the sensors 310. As an output from the second control unit45, there is sent a decision 350, i.e. a controlling of the auxiliarybrakes 60 for example or a throttle opening for the vehicle.

1. A motor vehicle comprising an internal combustion engine and anelectronic control unit (48) for controlling the engine depending on thesetting of a manual throttle control, a transmission, and an electroniccontrol unit (45) for controlling the transmission, depending on a setposition of a manually operated electronic gear selector (46),characterized in that one of the control units is disposed, with fed-inparameters and thus at least knowledge of the target speed of thevehicle, the surrounding topology and the throttle opening position, toreduce the throttle opening, in those cases where the vehicle, relativeto the target speed, has a speed below target speed and gravity cansubsequently accelerate the vehicle, and use the kinetic energy of thevehicle, in those cases where the vehicle has a speed above target speedand gravity can subsequently retard the vehicle.
 2. Motor vehicleaccording to claim 1, characterized in that the instantaneous vehicleposition is determined by a GPS (350) (Global Positioning System) unitwhich is coupled to one of the control units for instantaneousdetermination of vehicle position.
 3. Motor vehicle according to claim2, characterized in that one of the control units is disposed to begiven information from an electronic map (340) on the topologysurrounding the vehicle.
 4. Motor vehicle according to claim 1,characterized in that one of the control units is disposed to be giveninformation from sensors (310), and, at least with knowledge ofinstantaneous vehicle position, speed and road incline, extrapolatethrough calculation, a future position of the vehicle.
 5. Motor vehicleaccording to claim 1, characterized in that the engine is coupled to aclutch (3) and an automated transmission (9) between the engine and thedriving wheels and is provided with at least an auxiliary brake. 6.Motor vehicle according to claim 1, characterized in that the derivativeand acceleration of the throttle opening position, the instantaneous orextrapolated value, representing the intentions of the driver, also incombination with a cruise control function, are parameters in a computersimulation connected to a gear selection strategy.
 7. Motor vehicleaccording to claim 1, characterized in that one of the control units isdisposed, with the aid of electronics and sensors, to limit the throttleopening increase of a cruise control at great speed deviations and whenthe road is inclined downhill.
 8. Motor vehicle according to claim 1,characterized in that one of the control units is disposed, with the aidof electronics and sensors, to keep the throttle open when the vehiclespeed is greater than that set in the cruise control and the vehicle isapproaching an uphill incline in which the reduction in speed would beso great that the maximum engine torque would not be able to acceleratethe vehicle before the vehicle speed has dropped to the target speed. 9.Motor vehicle according to claim 1, characterized in that one of thecontrol units is disposed, with the aid of electronics and data fromsensors, to adjust the throttle opening when the vehicle is approachingthe end of an uphill incline, and where the vehicle speed is less thanthe target speed, gradually adjusting to a future lesser throttleopening.
 10. Motor vehicle according to claim 1, characterized in thatone of the control units is disposed, with the aid of electronics andsensors, to adjust the throttle opening, when the vehicle approaches thebeginning of a downhill incline, to gradually adjust to a future lesserthrottle opening, i.e. the throttle opening which together with gravityand driving resistance will accelerate the vehicle to the target speedwithin a predetermined time period.
 11. Motor vehicle according to claim1, characterized in that one of the control units is disposed, with theaid of electronics and sensors, is disposed to adjust possibly appliedauxiliary brakes and possibly the throttle opening, as the vehicleapproaches the end of a downhill incline, to a future greater throttleopening required to maintain the target speed.
 12. Motor vehicleaccording to claim 1, characterized in that one of the control units isdisposed, with the aid of electronics and sensors, to adjust possiblyapplied auxiliary brakes and possibly the throttle opening, as thevehicle approaches the end of a downhill incline, so as to permit atemporary increase in speed, the maximum level of which is predeterminedin the second control unit.
 13. Motor vehicle according to claim 1,characterized in that one of the control units is disposed, with the aidof electronics and sensors, is disposed to release the auxiliary brakes,when the vehicle approaches an uphill incline and where the vehiclespeed exceeds the target speed, to not brake off energy since theretardation of the vehicle in the uphill incline will adapt the vehiclespeed to the target speed.